ANDROID: BACKPORT: arm64: Implement ioremap/iounmap hooks calling into KVM's MMIO guard

Implement the previously defined ioremap/iounmap hooks for arm64,
calling into KVM's MMIO guard if available.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Bug: 233587962
Change-Id: I86a78f8941fb60078fb873a34c5eb32830a00259
[willdeacon@: Add hypercall IDs and slab_is_available() check]
Signed-off-by: Will Deacon <willdeacon@google.com>
[ qperret@: Fixed context conflict ]
Signed-off-by: Quentin Perret <qperret@google.com>